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Repeatability indices for the Adams D-15 test for colour-normal and colour-defective adults
Jeffery K Hovis1, Shankaran Ramaswamy, Matthew Anderson
1School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.
Purpose:
The Adams desaturated D-15 test was administered to individuals with normal colour vision or with congenital red-green colour vision defects to establish the repeatability of the test.
Methods:
One hundred subjects with normal colour vision and 64 subjects with defective colour vision participated in the study. Results were analysed from two different sessions to determine the repeatability of the test for different pass/fail criteria. The test was scored using both visual inspection of the score sheet and the modified Colour Difference Vector analysis (CDV) program.
Results:
For both subject groups, the repeatability was lowest when a perfect arrangement was required for a pass and improved as more errors were allowed. The improvement in repeatability was greatest as the failure criterion changed from 'any mistake' to 'more than two crossings'. The kappa coefficient for the reliability of the defect classification was 0.38 for visual inspection and 0.59 for the CDV analysis. All the protans who failed the test at both sessions were classified correctly.
Conclusions:
Approximately 98 per cent of the colour-normals and 82 per cent of the colour-defectives would have the same pass/fail outcome on the Adams D-15 test conducted several days apart when the failure criterion was either one or more or two or more crossings. Individuals who make less than four crossings on the Adams D-15 should repeat the test to ensure confidence in the pass/fail result.
